Pressure sensitive labels have found their way into all areas of life. They are used as badges or name tags at social gatherings or conventions as well as employed as labels on heavy machinery listing all sorts of operating characteristics and/or model information and the like.
Conventionally, a pressure sensitive label is made up of three components. A first is a sheet of face stock which may be virtually any type of imprintable material, but frequently will be paper or plastic. A second component is the so-called release liner sheet. The release liner sheet is typically a sheet of paper or plastic material having one side coated with a release material such as silicone or the like.
The third component is a pressure sensitive adhesive which is disposed between the face stock sheet and the release liner and which adheres the two together. The adhesive system and the face stock are selected so that the adhesive will always cling and adhere to the face stock while it will only releasably adhere to the silicone coated surface of the release liner.
Thus, in use, information to be conveyed is typically inscribed on the face stock, and specifically on the side thereof remote from the release liner. Once the label is to be installed, the release liner is grasped separately from the face stock and the two peeled apart. The separated face stock sheet, with the adhesive still clinging to one side thereof, is then applied, adhesive side first, to a substrate to which the label is to be mounted. The adhesive will adhere the face stock sheet, and thus the inscription on one side thereof to the desired substrate in such a way that typically it can only be removed through destruction of the face stock sheet.
In some instances, particularly when pressure sensitive labels are being employed on machinery or the like, it is desirable to protect the inscription on the label from the surrounding environment as, for example, moisture, lubricants, and the like. This environmental forces could, in many instances, cause deterioration and/or smearing of the information printed on the face stock. In some instances, particularly where the face stock is made of paper, and these environmental influences could cause deterioration of the face stock itself.
In cases such as mentioned immediately preceding, additional steps may be taken to protect the image on the label. Specifically, the label may be inscribed and placed on the substrate in the manner mentioned previously. At that point, then, a transparent overlay with adhesive on one side thereof and typically formed of a transparent plastic, will be installed over the label and adhered to the substrate around the periphery of the label so as to provide a generally sealed pocket of transparent parent material about the entirety of the label, the label being readable through the overlay material by reason of the transparency of the latter.
A number of problems accompany this technique. For one, if the overlay is not placed on the label properly, it may be wrinkled and thus of unpleasing appearance. More importantly, the wrinkles may represent defects in the peripheral seal about the pocket and allow moisture, lubricants, etc. to penetrate the pocket. Perhaps even more importantly, the application of the overlay represents an additional step in the labeling process. That, in turn, represents additional expense to the user of a labeling system requiring image protection.
Thus, there is a real need for a pressure sensitive labeling system that provides for image protection and without the need for the application of an overlay. The present invention is directed to meeting that need.